(1) Field of the Invention
This invention relates to electrical control circuits for DC motors, and particularly to such controls on boats having DC powered trolling motors.
(2) Description of the Prior Art
Opening and closing switches under DC loads often results in arcing across the switch contacts, particularly with the inductive DC loads produced by DC powered motors. Many control circuits for DC motors use relay switches. The arcing across the contacts of the relay switch causes premature switch failure and degraded operation of the motor.
The electrical control circuit for starting and stopping a DC powered trolling motor on a bass boat is one commercial application where arcs may occur at switches. When a switch is opened or closed to start or stop the trolling motor, the inductive loads produced may be as high as 40 amps across double switch contacts connected in parallel. Arcing across the contacts may result in switch failure, or ignition of the gasoline fumes sometimes present in bass boats.
Another problem associated with the motor control circuits of trolling motors is the common practice before my invention of fixing a spring loaded momentary contact type switch to the bow of the boat as the control switch to activate the relay coil, close the relay switches, and start the motor. The fisherman must interrupt his fishing activities, move to the bow of the boat where the switch is, and remain, while holding the switch button down as long as he wants to operate the trolling motor. Additionally, many systems require a weight to be placed on the push button switch to complete a circuit to the batteries for charging.
Prior to filing this application, a search was conducted in the U.S. Patent and Trademark Office. That search developed the references listed below.
______________________________________ U.S. Pat. No. WALKER 2,637,769 HARRIS 2,877,733 MARLEY 3,196,638 REE 3,376,467 OSWALD 3,739,192 GUARASCI ET AL 3,751,719 ROLLER ET AL 3,889,625 RHORER ET AL 4,130,079 GILBERTSON 4,250,358 Great Britain Patents LUTZ 1,433,938 ______________________________________
Applicant does not regard these references as particularly pertinent D to his invention. They are cited herein in the event that the Examiner might determine that they are pertinent and relevant to the examination of this application. However, these references are examples of the prior art. WALKER, MARLEY, REE, OSWALD, GUARASCI ET AL, and LUTZ disclose arc suppression circuits. ROLLER ET AL, RHORER ET AL, HARRIS, and GILBERTSON disclose marine engine or trolling motor control circuits.